1. Field of the Invention
This invention relates in general to magnetic recording systems and, in particular, to a magnetic disk recording system in which the magnetic transducer is in contact with the storage medium at operating speed.
2. Description of the Prior Art
It has been recognized since the early days of moving magnetic storage systems that contact recording is desirable. R. L. Wallace, Jr. established the space loss relationship in his paper "The Reproduction of Magnetically Recorded Signals", Bell System Technical Journal, October, 1951, pp 1145-1173. This paper defines the spacing loss (i.e. loss of read signal amplitude) in terms of the distance d between the magnetic read head and the surface of the recording medium and the wavelength of the recorded signal.
Although contact is known to be a key factor in audio and video recording systems as well as floppy disks, in contrast, contact recording systems for high performance moving magnetic storage systems have not been widely used. The reason for this is that, in the moving magnetic recording system, the transducer must be capable of running on the same track for extended periods of time without damage to the recording medium. The contact recording systems for high speed moving magnetic recording that have been built have had the problem of excessive wear of both the magnetic transducer and the magnetic recording medium.
U.S. Pat. No. 4,225,892 to Bassett et al discloses a magnetoresistive read head which is deposited onto a single crystal sapphire substrate which has a particular crystallographic orientation as the wear surface.
IBM TDB June, 1984, p 496 by Kehr et al discloses a ferrite magnetic head having at least one surface formed of a single crystal manganese-zinc ferrite. The surface is etched to form a smooth pore-free surface.
The unexamined published Japanese patent application 57-207408 discloses the use of a single crystal corundum as a substrate for a magnetic head.
U.S. Pat. No. 3,919,717 to Cullen et al shows a wear resistant surface for magnetic heads comprising diamond particles in a matrix of a softer material such as rhodium, for example.
None of the references disclose a contact recording system which utilizes a single crystal material having the physical characteristics required to hold the slider in contact with the recording medium without external force during high speed recording and sensing operations.